4a Work in groups of four. Do the quiz. 7 Which is the world's smallest continent?2 Which continent has the world's highest mountains?3 Which continent has the most countries?4 Which is the planet's longest river?5 What is the planet's biggest lake?6 Which is the world's smallest country?7 Which is the country with the largest population?8 Which is the world's largest country?​

1. The pupils ( discussed) this problem yesterday. 2. The pupils (were discussing) this problem the whole evening yesterday. 3. They  (were discussing) this problem from three till five o'clock. 4. They (were discussing) this problem at four o'clock yesterday. 5. They (were discussing) this problem when I came in. 6. She ( learnt) a poem yesterday. 7. She (was learning) a poem at five o'clock yesterday. 8. She (was learning) a poem from five till six o'clock 9. She (was learning) a poem when mother opened the door. 10. She (was learning) a poem the whole day yesterday. 11. I (did not to see) him yesterday. I ( saw) him two days ago. 12. She (was not  writing) a at seven o'clock yesterday. She (wrote) two days ago. 13. Jane (was reading) the magazine from five till six o'clock last evening. 14. He  studied) a rule in the morning last Monday. 15. Last month our team ( lost) the game. 16. what was she ( doing) when the telephone rang? 17. Whom were they ( speaking) to when I met them at the station? 18. They (were having) lunch when the telephone rang 19. Nick (was making) a report at three o'clock yesterday. 20. Mike (was writing) on the blackboard when I came into the classroom. 21. She (was not  sleeping) the whole night yesterday. 22. Who entered the room when you (were watching) television? 23. What were you ( thinking) about when I asked you a question?